Valves



May 2, 1961 Filed June 1, 1956 C. M. PETERS ET AL 2 Sheets-S' eet 1 VALVES INVENTORJ` ATTORNEYS May 2, 1961 Filed June l, 1956 C. M. PETERS E'I'AL VALVES @wat 2 tubing'mandrel.'

cintura M. Peten and Robert w. pinning, both of 1 Pv.O.-Box 2427, Longview, Tex. s p Filed June 1, 1`9`56, s`r.fN -sss,7-4fs 11 claims. l '(Cl. 1034233) VThis invention yrelates to' valves and more particularly to valvesinwhich Vthe valve member is substantially balanced, f that is, either upstreamcor downstream pressure N N United States PatentO 2,982,226 Patented, Mr 23, 12961 Linvertical section through a well bore'illustrating the sys- 'Y tem of this invention employing valves which open and has little 'or' no affect on opening or closingof the valve s membern even though the valve member reciprocates in the llow passageway. In gas lift valves, the valve member reciprocates in the llow passageway through the valve@ Thus, casing pressure and tubing pressure are normally effective on the valve member. As oil is lifted `in the ltubing, the tubing pressure on the `valv`e decreases. Casing Apressure will also varywhile the valve is open. `These two variables render it 'desirable in some cases, particularly in hhigh volume valves, to balance 4the valve member so that the elect of either tubing or casing pressureiscancelled out. In this way, the valve will open and close only in accordance with changes in'tubing or casing pressure depending upon whether the valve is operated byA changes in casing pressure or tubing pressure.

This balancing feature =has heretofore' been provided by a piston exposed to casingand tubing pressure on op-A posi-te sides ofthe piston.V 2,The piston is connected to the valve member fonfthe lside Qlpsite V.the means urging l vthe valve toward 'its""seat .g The'lpressure surfaces of thev close -in response to changesin tubing pressure;

Fig; 2A is a view'partly in elevation-and partly inseetion of the head piece ofa valve embodying this inven tion;` y .Y

' Fig. 2B is a continuation jof Fig. ZA- in crosssection illustrating a form of valve controlled by changes in casing pressure; t t

Fig. 3 is a view along the lines 3 3 of Fig. 2B; and e Fig; 4 is a view in cross-section through 4a form Aof foot piece to be used with the head piece shown in Fig. 2A to provide a valve operating in response to chan-ges intubing pressure. f

Valves constructed in accordance'withthis invention may -be either casing operated or Vtubing'operated.V In

; the casing operated val-ve, tubing pressure has little-'or piston and the vvalve-inember are vreversed so that either tubing orcasng pressure vis'balanced out ldepending upon the vmanner in which v,the valve is designed.' Thebalancmakes itlmore expensive to manu-facture.

. ing piston"heretofo're used'complicates the valve and v passageway'connecting the"outle t `from the'fvalve tothe inletof thetubing has been in the side wall .of thejtubular valve bodyr necessitating aspecial Vinandrel having annular seals above and ,belowthisl sidewall outlet. Inl valves designed for coventionalmandrel's, the outlet frornthe" valve body is at one end sothat asimple form of connection and seal may-be provided between the '.valve vbody and mandrel. "v This is a much simpler, less expeusivecont struction.

1t is anY objereo'f` this inventiqnn lproviae a balanced pressure valvei-which is much simplerand less expensive than conventional-balanced,pressure valves. s 0 V "Anotherjobject is ,toj provideavalve in which pressurev sand andcause oil to :ilow .into the-.welll v In many tcases utf isldesirable to place the well onfproduction asgso'on .as

In the well bore illustrated in Fig. l, strings "of 'casl ing 10 andv production-tubing 11 are' provided. The

space .between the casing and tubing 'is Lpaekecl olf'by packer 123 `above=the producing formationKnotjshoWnL Anplurality of dumping valvesl` anda-lowerllworldgvalve 14-*are carried1on the string of tubing-fbyflspacedconventional mandrels. ,15. Gas is injectediritofthe-ca'sing annul-us through conduit 16 and v'fed into tubing A15w through the severalvalves. l t -f When the well is `first placed-on productionythetubng wi-ll normallybe -full of liquid and' it is desired yto dump the contents fof the tubing and casing asurapidly aslyposl sible kto quicklyfgetion production; Thisfhydrostatio head Aof liuid' withi'n the tubing must' bel reformed"beforefn a differential caribe establishedacro'ss. the-facef-of tliefoilE -possibl'efzsov that the` 'well .can malte its allowable. n* marginal, wells, the rate'of production 'may .bei soilowtliat time is of the essence in obtaining the allowablefor"the`| v well. For these. and other reasonswhich makeLi-t-Ide'sirable to place a wellen .productionas Irapidlylasl possible,

.the dumping `valves 13 -are provided with'frela'tivelyZ oni'one side of the valve v seat' does not substantially. f

aiectopening and closing of'a valve member reciprocal kin `the flow passagewaythrough-the valve without/the necess'ity of laddinga v`separate balaneing piston. i,

Anotherobject lisito provid whichopensfland closes in response to changes in tubing pressure andwhich fma'y' be `mounted .'in a conventional Another' objeet n e e in vwhich the pressure `dop is,taken across, a ,restricted pora `balanced pressure valve isft't'lo provide la balanced pressurei valve lated` ).liquid ftherefrom. After the tubing V has beenl dumped; however, it lis desirable tos-.-regulate.tlierategatr `vvh-:iclfl gasilows into the tubingl.to.produce`fthetrnaximurrif amount, 0f1oi1 withV amini'rnumwolume -offgasy Excessive' gas gives an; inefficient ratiotof oilz'pei unit :off gas.

finJi insuicient yrateof -ow :will :noti provide, `'slug or pistoni ofl,gas to :lift 4oil in the tubingfwithoutexcessive?slipp Mge and consequent-1reducedzsrate..of"recovery: Thus* tlief' VWorking valve port `should be dimensioned ltoprovide tubing for the4 given Ywell conditions substantially` the Voptimumw rateoffiowf fgasjinto the provided'with'alchargingnplug`20 at one end to permit charging of the bellows. The bellowsis protected against excessive well pressure by trapping liquid behind the bellows as the valve member opens. As shown, the liquid levelis above a'seat 21 with which O-ring 22, carried by the bellows, forms av seal as the valve member moves to openfposition Vto trap a portion of the liquid behind the bellowstoprotect it against excessive pressure.

A guide 23 forms a part of a valvestem which interconnects the bellows with valve member 24. Valve memberl 24 is provided ;by an elongated member 25, one end of which is connected to guide 23. The upper portionv of member 2S above seal 26 may be con- Vsidered a part of the valve stem and the lower portion below seal 26. may be considered a part of'the valve member. Seal 26 is preferably a sliding seal and may be provided in any `desired manner, such as by an O-ring preferably carried by the member as shown.

The guide 23 is hollow and a port 27 establishes com-4 munication between the interior and the exterior of the guide.` The area insideand'outside of the hollow valve guide may be packed with grease to protect the bellows as is understood by those skilled in the art.

,v The head may be considered -to terminate in nipple 28 and in valve guide 23 as its design is such as to make-up with any of the lower valve foot parts shown in Fig. 2B and Fig.4. The function of the valve head is to provide a resilient means urging -the valve member of the foot piece toward closed position preferably by exerting a force on one side of a pressure responsive member such as bellows 19 which is exposed on its other side yto either casing or tubing pressure which will appear more fully hereinafter. While a special general purpose motor is shown for each of the illustrated valves, it will be understood that any -desired conventional form of motor may be used with .this invention.

. Referring now to Fig. 2B, the foot piece shown is used in wells where -it is desired to control opening and closing of the valve by variation in casing pressure. The body 29 of the footpieceA includes a connecting nipple 30 and is-.provided with a flow passageway therethrough forY introducing gas'from'the casing into the tubing. This passageway includes' an inlet passagewayv 31, a valve chamber 32, in which valve member 24 reciprocates, and a plurality of outlets 33 from the valve chamber .32. It willbe noted that the outlet passageways 33 parallel a portion of inlet passageway 31. Byy providing for this reversal `of direction Vof the ow. passageway, a very simple form of balanced valve maypbe provided. Gas from the casing leaves passageways 33 and is introduced intothe tubingthrough an adapter nipple 34. Nipple 3 4 hasta male end 35Y adapted to be connected to mandrelA 15, on ifdesired, adapter nipple 34 may be connected to," a check valve betweenrthe nipple and mandrel to prevent back flow of vuid from the tubing to the casing as is conventional practice in many installations.

. Returning to the owV passageway, the sum of the cross-sectional area of the sever-al portions 33 of the passagewayis preferably less than the cross-sectional area of any portion ofi the passageway upstream thereof.

'Ihus,. with the valve open, substantially all of the pressure'drop between casing and ltubing pressure will be takenyacross passagewayportions 33 and casing pressure will-be present in inlet 31 and in valve chamber 32.` In ,this way casing pressure will always be exerted upon lthe valve member 24 and the eiect of the Vdrop betweenA casing and'tubing pressure which occurs in the conventional valve at the valve seat, 'will not affect the opening and closing pressure of the valve member. i'

:,.Toinsure thattubing pressure does no t aiect opening and. closing ofthe valve member and that the eifective area of the valve memberexposed to casingpressure will;

befthesamc with the valve member both "in, open and er ein,... ...tx L l .2,982,2aav

" For'the specific structure s hown in' Fig; 2B; this crosssectional area within the sliding seal 26 will be equal to the cross-sectional area of bore 30a through connecting nipple 30 and, therefore, stated in another manner, the cross-sectional area of the valve seat is made equal to the cross-sectional area of bore 30a. Therefore, with the seat area being equal to the area of bore 30a and with the valve closed, therefwill'. be no net eiective area on the valve member or stem against which tubing or valve outlet pressure in chamber 32 can act to effectively urge the valve -toward either open or closed position. Stated in another manner,A all endwise facing areas on the valve member or stem between seal 26 vand seat 36 will have equal and oppositely facing counterparts so that any endwise force; resulting -from Vtubing pressure acting on one such area will be counterbalanced by the same tubing pressure acting on an equal but oppositely facing area. This is by virtue of making the seat and seal areas equal. Once the valve member is unseated, casing pressureuisjpresent in valve chamber132 and is effective on the valve member over an area; equalv to that within slidingseal26. Y Stated Yin another manner, upon opening of the valve, pressure in chamber 32 changes from tubing pressure to substantially casing pressure because, as stated, passageway portions 33 are sized so that substantially all of the pressure drop between the casing and tubing 'istaken across these passageway portions and since chamber 32 is upstream thereof, the pressure in chamber 32 wiljl rise tosubstantiallylthat ofthe `casing. Hence with the valve closed, casing pressure actsV on the area of the valve member 24 within seat 36 to urge the valve open, and'with the valve open, casing pressure in chamber'32 still acts on an equal area to urge the 'valve member open. Thus, the effect of casing pressure on the valve member is the same with the valve member in open or closed position. EIf it is desired to'open the valve rapidly, the area within the slidingseal may belslightly larger than the' area of the valve seat so thatvcasingrpressure will act on a larger area upon' opening of lthe ,va1ve member to cause it to snap to. open position. This difference would beso small that the' areas would be substantially equal and only a slight increase in the amount of. bleed down of casing pressure to reseat the valve would be necessary. fr f In order that the pressure upstream of thevalve seat, that is the pressure'eiective onthe valve member also vbe eifective on the -bellow s19, the connecting nipple 30is provided with a` passageway 37 exposing the bellows to the same pressure towhch 'the end of the valve member is exposed. As casing or ambient pressure will bethe same about the body ofthe valve, the passageway 37 may open into the exterior of thev body and the bellows 19 will be subjectto the same pressure that exists in inlet 31.`

Recapitu-lating with, the Vvalve closed, (a) the tubing pressure is ineffective to open or close the valve no matter what value it Vmay have, (b) the casing pressure acts to urge the valve open by acting von (1l-the area of the valve member within `seat l36Vplus (2),the net annular area equal to the cross-sectiona'larea of, the bellows minus the area within seal'26, and (c) the char-gepressure in dome 18 acts to .urge the valve closedzby acting on an area equal to the Vcrosssectional area of the .belloWs.

With the valve open, '(d) lthe tubing pressure4 is' Astill ineffective because it is 'isolated from all movingrparts of the valve and casing Vpressurerexists .in chamber 32, (e) the casing pressure still acts on vthe same areas as out-lined in item (b) above, and (f) the charge pressure still acts on the same areas asI outlined in item' '(c) above. Valve seat 36 can be of the removable type as shown and a seallsuc'h as'O-ring 38 provided'betweenthe seat and body '29.' Acage 39 ts aboutthe valve member and providesy a spacer: between the valveseaty 436 and the endof connector nipple 30 to =hold the .valve seat in place my. 1 ...Le

after the valve seat assembledi cage, 39is provided la; Scali member 62 is, interposed 'with a plurality of ports 41 to permit free flow therethrough; v y

With-its large flow passageway and the eiect of tubing back pressure cancelled, the valve of Fig. 2B is particularly well adapted for intermitting service in low produotivity wells and most especially in deep wells. The large liow passageway permits the-valve to slugf or llift fluid from extreme `depths with maximum elcieucy and minimum slippage.` The main inlet gas port 31 in a commercial `form of the valve is one-half inch in diameter and provides for a large volume of gas to be introduced into the tubing.` t

In explaining the operation of the valve of Fig. 2B, it will be assumed that the valve is a working valve and the casing and tubing 11 have previously been cleared of liquid and the well is on normal production. The valve will be closedand a controller (not shown) will `build up pressure within the casingto where the casing pressure exerts a force on the valve member and bellows 19in excess of the force exerted in the pressure dome on bellows 19. and the valve member will open. As tubing 'pressure has beenbalanced out, it will not affect the opening of the valve member. As the valve member 24 is unseated, gas will iiow through the flow passageway provided 'byf inlet 3 1,` valve chamber 32 and outlet passageways 33 into thetubing. As the ilow passageway is of` large area, a lange volume ofgas will be introduced into the tubing which. will lift the column ofV uid above the working "valveof the. tubing. Aswcasing. pressure drops, the force exerted by casing pressure on the bellows 19 and valve member 24 will :be reduced to a value less than that exerted by. the pressure Within dome 18 and valve member 24 will Abe reseated. As the effective area of valve member.24 is the same with thefvalve open'or closed, that i's the area of seal 265 the valve member will close Withtmnimum bleed `downof casing. pressure. Y

With anupperrend 69 which may-ber'secured to connector= ,Y

nipplel 28; of. the head lofjFig.l 2Av as shown. Thefbellows iSlGXp'osed to` tubing pressure through one or more pas- S'g'tiwlys..V 61: in body59. t To confine this tubing pressure,

' between the bodyf59` and connector nippleZS.` l The Valve` foot is. provided .with-a llow passageway,

:therethrough by restricted inlet 63, valve; chamber 64j Passages Y.

passageway 6.1, CommuricationV between passageway and the ow passageway on the downstream side of seat 66 is Vprovided by one or more passageways 69 in seat insert 71. Casing pressure within valve' chamber 64 is exerted on equal and opposite areas on valve member 67. As there is no effective area for casing pressure to act on, casing pressure has no affect on the opening and closing characteristics of the valve member. As soon as a head of fluid has accumulated in the tubing sufficient to exert a force greater than the force ex-` erted by the pressure within dome 18, valve member 67 g will move toward open position and permit flow of gas from the casing into the tubing to lift the head of uid therein.' As gas ilow is restricted through inlet 63, the pressure drop between casing and tubing pressure will take place at this point and tubing pressure will be present within valve chamber 64V while the valveY -is open. With the valve open the effective area of the valvemember exposed to tubing pressure is the area of sliding seal 68. As this area is equal to the area of the valve seat, the effective area of the valve member exposed to tubing pressure both while open and closed is the same. As the pressure exerted by the hydrostatic head within the tubing drops below the pressure Within. dome 18, the valve member 67 will re-seat and permit the hydrostatic head Vwithin the tubing to again build up.`

From the above, it will be seen that the objects of this' invention have been attained. There has been provided` a very simple rugged form of balanced valve which eliminates the necessity for the addition of a balancing piston to the valve member. Such a valve has been provided which` maybe controlled by changes in either casing pressure or tubing pressure to permit control of the well by varying casing pressure or permitting the well itself to kick or open the valve as soon as a suitable column of fluid has'been collected above the working valve.V

The pressure drop between casing and tubingrpressure t lis taken at a point other than theV valve' seat which minimizes the cutting action of the gas on the valve seat.l l "Fhe'tubing operated form of valve shownin Fig. 4 is so designedl so that fit may be mounted in a conventional mandrel elirnmating the necessity for a special and y more "expensive mandrelrtwo mount the valve on a tubing string aslhasv been conventional practice in the past.Y The valve .may also be run on a wire line and landed in cham-r bergfequipment `such as shown at page 1897 of the 21st edition ofjComposite Catalog of Oil Field and Pipeline u Equipment, andin side pocket mandrels as shown atv` and outlet4 65g` "The restricted inlet :'63vis `smaller there l *any other` portion, of the, flow passageway and is smaller thanthe; valveA seat 66 with. which the valye` member 67,:

reciprocating in chamber 64, ycooperates -tov control: flow..

through the tiowpassageway.

iswithinthe seatl 66 when the valve is' closed;

page 925oftll1ez2r0th edition of the same work. 1 Y

There has also beenn provided a system forr gas Vlift operationwhch will quickly unload, andl then eiiiciently 'Y Fronithe foregoing it willV be seen thatthis invention; is one well adapted'toyattain all of the ends and objects. hereinabove set"forth,together with other advantages which are obvious andwhich are inherent to the apparatus-" v Y Itmwillf'be understood that certain features and sub-VV combinations are of utility and may be employed without reference Ato'other features and subcombinations. This Lis contemplated.Vl by and` is within the `scope of the claims.

As many possible embodiments may befmade of the invention without departing from the scope thereof, it'

" is to'lbefunvderstood that all matter herein set forth or shown inthe accompanying. drawings is to be interpretedas illustrative and not in alimitingrsense l In `operation-,fY the desired pressure is maintained'fwitha i v inithe casing"a'nnulus 'and4 the valve kicksor opens when the/hydrostatic head ofi-fluid withinthe tubing' exertsfa' predetermined! openingforceon. the end onth'efvalveA Y Y member 67 and on bellws`19; While thevalveyis closed,

'isl

l'lhe inventionhaving been described, Awhatfis claimedV -17.*I`nl awell system including r'st Iand second well conduifsdis'posed; infa :well bore, a gasvlift valve sys-Vlr temc ornp'risingfa7 plurality of upper pressure actuated; u jdumpingyvalyes andfa'lower pressure actuated working; .rvalr A1u 1111t `=11 Q11? the tir'st ronduit, vSaid .valresgbeinag openedl and closed by an'increase'and decrease of pres- A f7 sure within the first conduit, each of said valves having means for balncingvout the effect. of pressure in the second `conduit on the valve memberY and-a restricted inlet .of less cross-sectional area than the valve seat so that the pressure drop between the first and second conduits is taken at the inlet and pressure in the second conduit has no effect on opening and closing of the valves, the inlets of the dumping valves having a greater crosslsectional area than the inlet of the working valve to provide Vfor rapid unloading through the dumping valves and efficient production utilizing the working valve.

2` In a well system including a well tubing and casing spacedly surrounding said well tubing disposed in a well bore, a gas lift valve system comprising a plurality of upper pressure actuated dumping valves and a lower pressureactuated working valve mounted on the tubing, each of said valves comprising a body having a llow passageway therethrough communicating between thettubing and casing, a valve seat across the passageway, a valve member including a stem mounted for reciprocationpin the passageway and cooperable with the seat to control ow through the passageway, means controlling seating and unseating of the valve member including resilient means urging the valve member toward valve closing position and a pressure responsive member in the body connected to the valve member by said valve stem, passageway means exposing the pressure responsive member to the pressure in the iiow passageway on the tubing side of the valve seat to urge the valve member away from its seat, a seal between the valve stem and body intermediate the pressure responsive member and the valve seat and preventing uid ow along the valve stem, said valve member having a cross-sectional area within the seat which is equal to the effective cross-sectional area within said seal so that pressure on the casing side of the valve seat will have substantially no effect on operation of the valve, and a restriction in the ilow passageway on the casing side of the valve seat of smaller cross-sectional area than the valve seat limiting pressure on the valve member when unseated to tubing pressure, said restriction being of less cross-sectional area on the working valve than on the dumping valves.

3. A valve comprising a body having a connector at one end for connection with a ow tubing, a iiow passageway through the body having an inlet at the exterior jof the body and an outlet at said connector, a valve seat across the passageway, a valve member including a stern` mounted for reciprocation in the passageway and cooperable with the seat to control flow through the passageway, said seat being disposed transversely of the valve member so that pressure on one side of the s eat acts upon the area of the valve member within the seat to urge the valve member toward unseated position,

the valve member away from its seat, a seal lbetweenj the valve stem and body intermediate the valve seat and pressure responsive member and preventing uid iiow along the valve stem, the eiective cross-sectionalarearof said valve member within saidY seat when the valve member' is seated therein being substantially equalto the eiective area within said seal substantially balancing prmsure from fluid on the other side of the valve seat on equal vareas of the stem, seal and valve closure member in opposite directions when the valveV is seated,

whereby pressure on said, other side of .the valve seat has substantially noV eiect on operation of the valve.

A valve comprisinga body having a` connectorat* one end for connection with a ow tubing'a ilpwpas- .....MV l y sageway through the body having an inlet at the exterior of the body and an outlet at said connector, a valve seat across the passageway, a valve member including a stem mounted yfor reciprocation in the passageway and cooperable with the seat to control ilow through the passageway, said seat being disposed transversely of the valve member `so that pressure on one side of the seat acts upon the area of the valve member within the seat to urge the valve member toward unseated position, means controlling 'seating and unseating of the valve member including resilient means urging the valve member toward valve closing position with predetermined vforce and a pressure responsive member in the body connected to the valve member by said valve stem, passageway means in the valve exposing the pressure re sonsive member to the pressure in the flow passageway on said one side of the valve seat to urge the valve member away from its seat, means forming a sliding seal between the valve stem and body intermediate the valve seat and pressure responsive member and preventing fluid ow along Vthe valve stem, the effective area of said valve member within said seat when the valve member is seated therein being equal to the effective area within said seal means substantially balancing pressure from uid on the other side of the valve seat on equal areas of the stem, seal and valve closure member in opposite directions when the valve is seated so that pressure on the other side of the valve seat will have substantially no elect on operation of the valve, and a restriction in the iiow passageway on said other side of the valve seat of smaller cross-sectional area than that of the valve seat limiting pressure on the valve member when unseated to pressure on said one side of the valve seat.

5. A valve comprising a tubular body having a connector `at one end for connection with a ow tubing, a flow passageway through the body with its outlet at the connector and its inlet in the sidewall of the body, said passageway having parallel inlet and outlet portions interconnected by a valve chamber, a valve seat at the entrance of the inlet passageway portion to the chamber, a valve member reciprocal in the chamber and cooperable with the seat to control ow through the passageway, a pressure dome in the other end of the body formed in part by a pressure responsive member, a valve stem interconnecting the pressure responsive member and the valve member, a sliding seal between the body and valve stem preventing flow to and from the chamber along the valve stem, the area within the sliding seal being equal to the area of the valve seat so that pressure within the chamber will not exert a force on the valve member eiective to move it when the valve is of the inlet passageway portion to the chamber and disposed transversely of the valve member so that pressure on the upstream side of the seat acts upon the area of` thevalve member within `the seat to urge the valve member toward unseated position, a valveV member reciprocal in the chamber and cooperable with the valve seat to control flow through the passageway, a pressure dome in the other end of the body formed in part by a pressure responsive member, a valve stem interconnecting the pressure responsive member and the valve member, a sliding seal between the body yand valve stem preventing ilow to andfrom the chamber along the valve stem, the areaV within the sliding seal being equal to the area of the valve :both in its open andclosedpositions.

by Vequal .and opposite areas;l so that pressure within'the chamber: will not exerlt a force on the valve member'eiec- Y tive '5to move Vit'when the valve is closed, passageway means in the valve exposing thepressure responsive member and the valve stem on'the end'remote from' the chamber `to-ambient pressure, and'a restriction in the passagei way downstream of the valve seat of smaller cross-sectional area than that of` the valve seat limiting pressure on the valve'rnemb'er when'unsealted to pressure upstream of the seat.

` 7. A .valve comprising a body having a connector at 'oneend' for connection with a ow tubing, a flow passageway throughV the body having an inlet at the exterior of the body :andan outlet at the connector, a valve seat i acossthe passageway, a valve member'mounted on the dwnsteamside ofthe seat for reciprocation in the passageway and cooperablewiththe seat to control iow through" the"'passageway,said seat'being disposed trans- `intermediate the pressure responsive member and valve seat and preventing uid flow along the valve stern, the etective areawithin said sliding seal being equal to the area within the valve seat so that said valve member when seated has equall and opposite areas exposed to downstream pressure so that such downstream pressure will have no effect upon unseating of the valve, and a restriction in the flow passageway on the downstreamside of the valve seat of smaller cross-sectional area than the l valve seat so that upstream pressure will'be eiective on the valve member in both openand closed positions.

8. A valve comprising 'a bodyhaving a connector at one end for connection with a flow tubing, a flow passageway through the valve body having an inlet at the exterior of the body and an outlet at said connector, a valve seat across the passageway, a valve member including a stem mounted for reciprocation in the passageway upstream of the seat and cooperable with the seatto control flow through the passageway, said valve-seat being disposed transversely of thevvalve memberso that pressure downstream vof` the seat, when the valve memberis seated, acts to urgethe valve member to unseated posithe other, one of said sections communicating with'the interiorof said ow tubing through the connector and the other communicating with the exterior of said body; a -valve seat having an internal cross-sectional areasubstantially equal lto the lcross-sectional `area of the larger of said inlet and outlet sections disposed around the larger of said sections adjacent to said valve chamber; a valve stem v,disposed vfor, reciprocating movement in the valve chamber and in a bore in the body communicating therewith; a valve closure member carried on said valve stem in the valve chamber and cooperable with said valve seat to open and close the ow passageway; means controlling seating and unseating the valve member, including a pressure responsive member in the body connected tothe valve stem and resilient means for applying predetermined r force to the pressure responsive member urging the valve l Ydirection opposingsaid predetermined force; and a sliding seal between thevalve stemY and bodydisposed nsaid bioredntermediatej the valve: seat `and pressure' responsive member to prevent fluid tlow along the valve stem, the area within said seal being substantially equal to the area of said valve member within said seat when the valve member is seated, substantially balancing pressure from uid in the valve chamber on areas of the valve closure member and stem in opposite directions when the valve is seated whereby pressure in the valve chamber has substantiallyno etect in opening the valve.

10. A valve comprising a body having a connector at one end for connection -to -a ow tubing; a flow passageway through the body comprising sequentially an inlet section, an enlarged valve chamber within the body and an outlet section, said inlet section having electively larger Y total cross-sectional area than the outlet section, the outlet tion, ka pressure responsive member in the body connected t *to the valve member by said' valve stem, resilient means acting on one side ofthe pressure responsive member urg- 'ing it toward valve closing position with predetermined saidsliding `seal being equal to the 'areaof the valve seat V whereby pressure upstream of the valve seat willnot lalectv v the valve member when lseated, and a restriction in .theV

flow passageway upstream ofjthe valveseat-of smaller cross-sectional area than thevalveseat sojthatl downstream pressure will be eiective on the valve member i fan outlet section, oneof said inlet and outlet sections l having-effectivelyl larger total cross-,sectionalareaY than section communicating with the interior of said ow tubing through the connector and the inlet section communieating with the exterior of the body; a valve seat having an internal cross-sectional area substantially equal to the cross-sectional `area of the inlet section disposed around r the inlet section adjacent to said valve chamber; a'valve Vstem disposed for reciprocating movement in the valve to pressure in the inlet section to a surface of the pressure responsive member yin aY direction opposing said predetermined force; a sliding seal carried by the valve Vstern disposed in `said bore intermediate the valve seat and pressure responsivemember to prevent iiuid owV along the valve stem Ythrough the bore, the area Vvwithin Y said seal'tbeing substantially equal to the effective area of saidV valve member within said seat when thevalve member is seated, substantially balancing pressure from i ,s fluid in the valve chamber on areas ofthe valve closure i member, sternaand seal in opposite directions when thel valve is seated whereby vpressure in the valve` chamber has substantially no effect in opening the valve.

11. Afvalve comprising a body'having arconnector at g one end for connectionto a ow tubing; a flow passageway through-the bodyV` comprising sequentiallyanv inlet section,- anv enlarged valve chamber within the body,

and an outlet section-,said inlet section having eiectively f smaller cross-sectional area thanthe cross-sectional area ofthe outlet section .and communicating with a [space vexteriorof said ow tubing land said` body, said outlet i Il section communicating with the' interior of`sadow tubing through said connectionj a valve seatV having an internal cross-sectional `area substantially equal to the crosssectonal areaY of the outlet section disposed laround the outlet section adjacent to saidlvalve chamber; a valve stem disposed for reciprocating movement in the valve chamber and in a bore in a body communicating therewith; a valve closure member carried on said valve stem -in the valve'chamber cooperable with said valve seat to open and4 close the flow passageway; means controlling seating and unseating thevalve member, including a pressure responsive memberiin'the body connected to the valve stem and resilient means for applying predetermined force to the pressure responsive member urging the valve member toward valve closing position; a passageway in the body disposed to apply pressure substantially equal to pressure in the outlet section 'to a surface of the pressure responsive member in a direction opposing said predetermined force; and a sliding seal carried by the valve stem disposed insaid bore to seal between the valve stem and body intermediate the valve seat and pressure responsive member to prevent uid flow along the -valve stem, the effective area within said seal being substantially I2 equal to the eective area within said seat when the valve member is seated, substantially balancing pressure from fluid in the valve chamber on opposing areas of the valve closure member, stem and seal in opposite directions when the valve is seated whereby pressure in the valve chamber has substantially no effect on operation of the valve.

References Cited in the le 0f this patent UNITED STATES PATENTS Re. 24,015 Walton May 31, 1955 2,314,869 Boynton Mar. 30,1943 2,339,487 King Jan. 18, 1944 2,620,740 Garrett et al. Dec. 9, 1952 2,620,741 Garrett et al Dec. 9, 1952 2,629,335 Peters Feb. 2A, 1953 2,642,8'11 Fletcher June 23, 1953 2,691,383 Church Oct. 21, 1954 2,698,024 Canalizo Dec. 28, 1954 2,725,014 Y Pryor Nov. 29, 1955 2,731,977 McGowen Ian. 2A, 1956 2,797,700 McGowen July 2, 1957 

